|
|
Agency for Toxic Substances and Disease Registry
Case Studies in Environmental Medicine (CSEM)
Chromium Toxicity
Clinical Evaluation
- If chromium exposure is suspected, the respiratory system, kidneys, liver, and skin should be evaluated.
Often, no clear diagnostic clues exist in chromium-poisoned patients. A thorough history is therefore critical in evaluating a potentially exposed person. The patient's recent activities are important when health effects other than cancer are the major concern. Occupation, location of residence and workplace in relation to industrial facilities or hazardous waste sites, and source of drinking water supply should be investigated. In patients with known chronic chromium exposure, the physical examination should include evaluation of the respiratory system (if inhalation is involved), kidneys, liver, and skin.
Severe exposures to chromium compounds are usually accidental or suicidal, and are rarely occupational or environmental. Short-term, high-level exposure to Cr (VI) produces irritation at the site of contact, including ulcers of the skin, irritation of the nasal mucosa, perforation of the nasal septum, irritation of the gastrointestinal tract, impairment of olfactory sense, and discoloration (yellowing) of teeth and tongue.
- Ingestion of a lethal dose of chromate can result in cardiovascular collapse due to severe hypovolemia.
- Sublethal doses of chromate can lead to renal and hepatic necrosis 1 day to 4 days after ingestion.
About 1 gram (g) of potassium dichromate (VI) is considered a lethal dose. Persons who ingested 5g or more experienced gastrointestinal bleeding, massive fluid loss, and death within 12 hours after ingestion. When the ingested dose was 2 g or less, renal tubular necrosis or diffuse hepatic necrosis resulted, with acute renal failure before death in some cases. Typically, the kidney and liver effects develop 1 day to 4 days after ingestion of a sublethal dose. Other symptoms of acute Cr(VI) ingestion include vertigo, thirst, abdominal pain, and vomiting. Oliguria, anuria, shock, convulsions, coma, and death can ensue. Gastrointestinal hemorrhage and coagulopathy can also occur. Acute chromium poisonings are often fatal regardless of the therapy used.
Dermal contact with Cr (VI) compounds can result in severe systemic toxicity. In one case involving intact skin, antiscabies ointment containing Cr (VI) resulted in necrosis of skin at application sites, nausea, vomiting, shock, coma, and death. Two other cases involved broken skin: severe nephritis and death followed cauterization of an open wound with Cr (VI) oxide, and an occupational fatality was described after an accident in which a worker was burned on the arms and trunk with hot potassium dichromate.
- In occupational settings, the most commonly reported effects of chronic chromium exposure are contact dermatitis and irritation and ulceration of the nasal mucosa.
- Less common are reports of hepatic and renal damage and pulmonary effects.
- Lung cancer is a potential long-term effect of chronic Cr (VI) exposure.
Repeated skin contact with chromium dusts can lead to incapacitating eczematous dermatitis with edema. Chromate dusts can also produce irritation of the conjunctiva and mucous membranes, nasal ulcers and perforations, keratitis, gingivitis, and periodontitis. When a solution of chromate contacts the skin, it can produce penetrating lesions known as chrome holes or chrome ulcers, particularly in areas where a break in the epidermis is already present. These ulcers are usually painless, but might persist for months. Acute hepatitis with jaundice has also been observed in workers chronically exposed to Cr (VI). Lung cancer is the most serious long-term effect.
Low-level environmental exposures have not resulted in adverse effects in human populations. Long-term studies in which animals have been exposed to low levels of chromium in food or water have produced no harmful effects.
A general medical workup for a patient with suspected chronic chromium exposure might include the following:
- Complete blood count
- Blood panel
- Liver function tests (AST or SGOT, ALT or SGPT, and bilirubin)
- Blood urea nitrogen (BUN) and creatinine
- Urinalysis
- Blood and urine chromium levels
- β2 microglobulin.
If chromium inhalation has occurred, a chest radiograph, pulmonary function testing, and a nasal smear for eosinophils should be included.
When obtaining biologic specimens for chromium analysis, care must be taken to avoid sample contamination and chromium loss during collection, transportation, and storage. For example, use of stainless steel utensils to collect tissue samples might raise tissue chromium levels, as will stainless steel grinding and homogenizing equipment. Some plastic containers contain significant amounts of leachable chromium; therefore, specially prepared acid-washed containers should be obtained from the laboratory. Considerable care also must be taken in the analysis to minimize chromium volatilization during sample ashing.
Another difficulty in the available techniques is the inability to distinguish between Cr (III) and Cr (VI). This is particularly important in environmental samples because Cr (VI) has been associated with serious health hazards, whereas Cr (III) is of far less concern.
- Chromium can be measured in blood and urine; hair or nail analysis has no clinical value.
Blood distribution of chromium appears to be divided evenly between plasma and erythrocytes. In the absence of known exposure, whole blood chromium concentrations are in the range of 2.0 µg/100 mL to 3.0 µg/100 mL; lower levels occur in rural areas, and higher levels occur in large urban centers. Values above background levels are considered potentially toxic, but levels have not been correlated with specific physiologic effects. Chromium rapidly clears from the blood, and measurements relate only to recent exposure.
- Urinary chromium excretion is a useful index of exposure in occupational settings.
Wide individual variation in metabolism and rapid depletion of body burden limit the value of urinary chromium monitoring. Urinary chromium excretion reflects absorption over the previous 1 or 2 days only. If sufficient time has elapsed for urinary clearance, a negative biomonitoring result can occur even with injurious past exposure. Assuming no source of excessive exposure, urinary chromium values are typically less than 10 µg for a 24-hour period.
In occupational settings, a urinary chromium concentration of 40 µg/L to 50 µg/L immediately after a work shift reflects exposure to air levels of 50 µg/m3 of soluble Cr (VI) compounds, a concentration associated with nasal perforations in some studies. The American Conference of Governmental Industrial Hygienists has set a workplace biologic exposure index for total urinary chromium as follows: no more than 10 µg chromiu per gram creatinine increase during a work shift, and a urinary value of less than 30 µg chromium per gram creatinine at the end of the work week.
Hair or nail analysis is of little use in evaluating an individual patient because it is impossible to distinguish chromium bound within the hair during protein synthesis from chromium deposited on the hair from dust, water, or other external sources. Populations with no known chromium exposure reportedly have hair levels ranging from 50 parts per million (ppm) to 100 ppm chromium.
The presence of chromium and chromium complexes in biologic complexes can be determined using chromatographic and colorimetric techniques; patch testing and lymphocyte proliferation testing have been used to determine chromium sensitivity.
| 6. |
Analysis of the tap water in the patient's home reveals a greenish tinge and a chromium concentration of 746 µg/L. Your diagnosis is chromium toxicity. Are there any other tests the patient should undergo? |
| 7. |
The patient described in the case study insists on obtaining a hair analysis. The chromium content of the hair sample is 1,038 ppm. How will you interpret this result? |
Previous Section
Next Section
|
